UCSD study finds men and women process pain differently

Last Updated on May 1, 2025

Women have more chronic pain and are less responsive to opioid treatments.

Researchers at the UC San Diego School of Medicine have discovered that men and women utilize different biological systems to relieve pain.

The findings, released in a new study evaluating meditation for chronic lower back pain, discovered that while men relieve pain by releasing endogenous opioids, the body’s natural painkillers, women rely instead on other, non-opioid based pathways.

Synthetic opioid drugs, such as morphine and fentanyl, are the most powerful class of painkilling drugs available but carry a significant risk of dependence and addiction.

Women are known to respond poorly to opioid therapies, which may explain why they are more likely to become addicted to opioids.

“Dependence develops because people start taking more opioids when their original dosage stops working,” Fadel Zeidan, professor of anesthesiology and endowed professor at UCSD Sanford Institute for Empathy and Compassion, said in a press release.

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The study combined data from two clinical trials involving 98 participants, both healthy individuals and those diagnosed with chronic lower back pain. Participants underwent a meditation training program, then practiced meditation while receiving either placebo or a high-dose of naloxone, a drug that stops both synthetic and endogenous opioids from working.

At the same time, participants experienced a very painful but harmless heat stimulus to the back of the leg. The researchers measured and compared how much pain relief was experienced from meditation when the opioid system was blocked versus when it was intact.

The team found that naloxone use inhibited meditation-based pain relief in men but increased it in women, and both men and women with chronic pain experienced more pain relief from meditation than healthy participants.

“These results underscore the need for more sex-specific pain therapies, because many of the treatments we use don’t work nearly as well for women as they do for men,” said Zeidan.

The researchers conclude that by tailoring pain treatment to whether a patient is female or male, it may be possible to improve patient outcomes and reduce the reliance on and misuse of opioids.

“There are clear disparities in how pain is managed between men and women, but we haven’t seen a clear biological difference in the use of their endogenous systems before now,” Zeidan said. “This study provides the first clear evidence that sex-based differences in pain processing are real and need to be taken more seriously when developing and prescribing treatment for pain.”